1. Field of the Invention
This invention relates in general to the manufacture of semiconductor wafers and more specifically to an improved process for the deposition of films on the semiconductor wafers.
2. Description of the Related Art
High temperature low pressure chemical vapor deposition (LPCVD) is utilized for the deposition of films on semiconductor wafers. In one example, silicon nitrides and silicon oxynitrides are deposited on semiconductor wafers by LPCVD to form structures on a semiconductor wafer such as gate spacers and anti-reflective coating (ARC).
With some LPCVD processes, it may become necessary to reduce the deposition temperature in order to minimize dopant diffusion (e.g. in the extension region), dopant de-activation, and/or recrystallization. However, for some film types, depositing an LPCVD film at a lower temperature on a batch of wafers may increase the number of defects in LPCVD films deposited on sequential batches. For example, the deposition of LPCVD silicon nitride on a batch of wafers at 720 C in a furnace may cause defects to occur on an LPCVD silicon nitride film subsequently deposited on another wafer batch in the same furnace.
What is needed in an improved technique for the manufacture of semiconductor wafers.
The use of the same reference symbols in different drawings indicates identical items unless otherwise noted.